1. Field of the Invention
The present invention relates to a light-to-light conversion method for use in display units, optical computers, etc. and a display unit using such light-to-light conversion method. It is also concerned with a light-to-light conversion element incorporated in the display unit.
2. Description of the Related Art
Various display units are known in which a light beam modulated in its intensity in accordance with time sequential information signals is projected onto a screen via projection optical system, thereby providing a two-dimensional display of an image on the screen.
The prior display units are, however, only applicable with a particular image source. For instance, cathode ray tubes are unable to reproduce those sources other than video signals. Similarly, moving picture projectors can only reproduce movie films. In addition, electro-cinematographic systems are used With a particular information recording medium.
An improved display unit is proposed by the present assignee as described in the co-pending U.S. patent application Ser. No. 633,223, filed Dec. 24, 1990, entitled "Method of Information Conversion and Apparatus thereof".
The proposed display unit is generally satisfactory. However, it still has drawbacks. For example, the response rate of a linear modulator element is relatively low and that an additional image-forming optical system is needed to two-dimensionally project a modulated linear beam onto the input side of a light-to-light conversion element.